Solenoid insert bobbin



May 22, 1962 R. 1.. VALLEAU SOLENOID INSERT BOBBIN Filed Aug. 18, 1958 INVENTOR. [20b '1 L. Val leau United States Patent M 3,036,246 SOLENOID INSERT BOBBIN Robert L. Valleau, Chicago, 111., assignor to Comar Electrio Company, Chicago, 111., a corporation of Illinois Filed Aug. 18, 1958, Ser. No. 755,541 4 Claims. (Cl. 317-158) This invention has as its principal object the provision of an improved coil bobbin and means for mounting the same in a magnetic frame piece for use in electromagnetic solenoids and relays.

Coils for relays, solenoids, transformers and related equipment are commonly wound on a bobbin or form having an open core which is later slipped onto an armature or pole piece.

Some types of solenoid, for example, are wound directly on paper-insulated brass cores; others are wound on paper or like tubes and slipped onto grass liners and provided with moulded headers of fiber, or Bakelite, at both ends; still others are wound on moulded plastic forms.

Commonly, the simpler types of solenoid, such as used in small pawl and ratchet mechanisms for stepping switches and counters, are provided at one end with a magnetic slug or heel piece which acts as a stop and/or completes the magnetic circuit for the plunger, and such solenoids may be mounted on the magnetic frame or other chassis or mounting bracket by means of a screw or rivet engaged in the outer end of the heel plug.

The present improvements relate to the provision of a moulded bobbin and a special magnetic frame piece adapted to receive, seat, and orient the coil by a simple snap-in construction which saves time, material, and expenses in assembling the solenoid coil on its frame, and which also makes it possible to turn the coil to locate the terminal lugs selectively.

Other objects and aspects of novelty and utility pertani to details of the construction described hereafter in view of the annexed drawing in which:

FIG. 1 is a perspective view of an assembled solenoid coil and frame with plunger shown in dotted lines;

FIG. 2 is a view similar to FIG. 1 showing the coil and frame separated;

FIG. 3 is a vertical section through the frame coil bobbin and plunger;

FIG. 4 is a perspective of the coil bobbin;

FIG. 5 is a top plan view of the frame showing the bobbin entrance slots and seat.

The solenoid, as the term is here used, consists of a bobbin form 10, such as depicted in FIG. 4, upon which has been wound the wire coil 12, as shown in FIG. 2, the ends of which are led and soldered to a pair of terminal lugs 14 moulded into the bottom header 16.

The bobbin form is a one-piece moulded product made of a suitable thermoplastic material such .as nylon having some inherent yieldability, for reasons to appear.

As viewed in FIG. 4, the bobbin consists of a tubular section 11 terminating at its lower end in the bottom header 16, which is provided with an extended portion or terminal board 15, in which the lugs 14 are embedded.

Spaced from a neck 17 at the upper end of the tubular section 11 is an upper circular header portion 18 having integral locating wings 20 projecting radially from the neck at positions correspondingto desired locations or orientations of the terminal board or lugs 14, as indicated by the dotted-line positions portrayed in FIG. 1.

The bobbin 10 is intended to be used with a magnetically conductive frame structure 25 (FIG. 2) which is of U-shaped configuration including upper and lower arms 26 and 27, respectively, joined by a bight portion 28.

This frame differs from other frames in that the upper 3,036,246 Patented May 22, 1962 arm 26 is provided with a wedge-shaped slot 30 leading from a wide entrance at the edge of the arm radially inward to narrow into conjunction with a circular seat 31 (FIGS. 2 and 5) for the protruding neck 17 of the bobbin (FIGS. 1 and 3).

A small locating notch 32 is provided in the neck seat lying on, and extending in the same direction as, the radius contained within the larger tapered or wedgeshaped entrance slot 30, and is of a size and shape to receive one of the radial wings or projections 20 on the bobbin, as depicted in FIGS. 1 and 3.

Referring to FIG. 5, the formation of the circular seat 31 and the tapered entrance slot 30 is such that at the conjunction 33 of these portions it is slightly less than the diameter of the bobbin neck 17, so that in order to pass the neck into the seat a moderate pressing forcev must be applied to clear this narrowed region. It is for this reason that the bobbin is fabricated from a material having some yieldability with form-retaining properties to spring back always to its original shape, and for this purpose the nylon class of thermoplastic is quite satisfactory.

The complete solenoid coil is shown in FIG. 2 in a position to enter (or separate from) the frame; and the dotted-line showing in FIG. 1 illustrates how the orientation may be changed to position the terminals 14 in an opposite position. By exerting a simple pressure on the coil, the neck 17 will snap past the slight restriction at 33 and seat itself in the slot hole 31. The wing 20 in notch 32 will prevent change of position.

The assembly will usually be completed, as in FIG. 3, by the insertion into the bottom of tubular bore 11 of a small ferromagnetic plug or heel piece 40 bored and tapered to receive a retaining screw 41. The solenoid plunger 42 is shown in the usual attracted (inward) position in FIG. 3, and in a relatively outward (unattracted) position in dotted-lines in FIG. 1.

The nylon tube 11 affords an excellent sliding bearing for the plunger. In those cases where there is no expectation of changing coils 12. or the orientation thereof, the assembly is made permanent for production purposes by riveting the heel piece 40 in position (not illustrated).

I claim:

1. An electromagnetic coil bobbin comprising a onepiece molded form consisting of a tubular core section having an integrally-formed header portion adjacent each of its opposite ends and lying in a plane at right angles to the tube axis and defining with the tubular section a winding spool, said tubular section protruding axially a short distance beyond one of said header portions to afford a thin-walled tubular neck projection, said bobbin form being molded of a thermoplastic composition which provides a substantial yieldability at least in the wall portion of said neck so that the latter can yield in a radial sense relative to said axis to permit pressing the neck radially into a complementary circular seating opening of a type having a radially sidewise entrance slightly narrower than the diameter of the neck requiring the latter to be forced into the opening.

2. A bobbin according to claim 5 further characterized in that the header portion which is at the opposite end of the bobbin from the neck has a radially-extended terminal portion with terminal lug means molded therein, and said header portion at the neck end of the bobbin has at least one integrally-formed, radially-directed locating'lug lying above the plane of the outermost surface of one said header portion and adapted to coact with a complementary formation in said neck seat to dispose said terminals in a certain position angularly about an axis through said tubular section.

3. An electromagnetic coil bobbin and frame structure comprising a bobbin form made from a. nylon-type of aosasae plastic having a tubular neck portion with a wall thickness thin enough to be yieldable in a diametric and radial sense to .a deforming pressure and projecting axially beyond a header formation at one end thereof, and a frame structure including an arm adapted to overlie said header and having a rounded opening therethrough comprising a seat into which said neck fits closely and an entrance slot communicating from a widened entrance portion at an edge of the arm and narrowing radially into conjunction with said sea-t opening with a snap-in fit at said conjunction whereby said neck may be pressed into and out" of said seat with a sort of snap-action, and removable means on said frame structure engageable with the tubular end portion of the bobbin opposite said neck for retaining the bobbin in assembly cooperably with the seating of the neck in the first-mentioned arm, as set forth.

4. .In an electromagnetic device of the type including a coil bobbin and a magnetic frame carrying said bobbin, improvements comprising, namely: a bobbin includinga core tube having a header portions'ubstantially at each of the opposite axial ends thereof and each extending in a plane substantially at right angles to the axis of the tube, one endportion of said tube extending as a neck a short distance outwardly beyond the plane of one of said headers, and having at least one projection lying above said planeandextendin g radially beyond the periphery of thetube'; and aU- shape d magnetic frame comprising a bight portion with an offset arm at each end thereof characterized in. that one of said arms has a hole therethrough of a size to snugly receive said tube neck and said arm is provided with a tap'e'red' assa e leading inwardly from and through an edge poitionthereof into narrowing conjunction with said hole of sufficient width at the juncture to pass said neck by a form of snap action by application of moderate force thereto int6 seated condition in said hole, the remaining arm of the frame being spaced from the first-mentioned arm to closely underly the remaining header and tube portion of the bobbin in the snapped-in condition thereof aforesaid; said first-mentioned frame arm having a radial slot leading from a margin of said hole in an approximately radial sense oppositely away from said entrance notch and of a size to receive said neck projection to orient the bobbin in a predetermined position relative to the frame.

References Cited in the file ofthis patent UNITED STATES :PATENTS 7 1,647,039 Fischer .Oct. 25, 1927 Dorst June 17, 8

UNITED STATES PATENT OFFICE CERTIFICATE CORRECTION Patent No. 3,036,246 May 22, 1962 Robert L. Valleau It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 18, for "grass" read brass column 2 llne 34, for "tapered" read tapped same column 2 llne 60, for the claim reference numeral 5" read 1 Signed and sealed this 30th day of October 1962.

:SEAL) Attest:

ERNEST w. swmsn DAVID L- LADD Attesting Offioel' Commissioner of Patents 

